Isolation and characterization of bacteria associated with silkworm gut under antibiotic-treated larval feeding

The impact of antibiotics on growth, cocoon production was assessed in addition to isolation and characterization of bacteria associated with silkworm gut of infected larvae. Larval rearing was maintained at recommended conditions of temperature and humidity. Silkworm larvae showing abnormal symptoms were collected from the control group and dissected for gut collection. Bacteria were isolated from the gut content by spreading on agar plates and incubated at 37 °C for 48 hrs. Bacterial identification and phylogenetic analysis were carried out by 16S rRNA gene sequencing. The isolated bacteria were subjected to antimicrobial susceptibility test (disc diffusion methods) by using Penicillin (10 µg/mL), Tetracycline (30 µg/mL), Amoxicillin (25 µg/mL), Ampicillin (10 µg/mL), and Erythromycin (15 µg/mL). All isolated strains showed positive results for the catalase test. We isolated and identified bacterial strains (n = 06) from the gut of healthy and diseased silkworm larvae. Based on the 16S rRNA gene sequence, isolated bacteria showed close relation with Serratia, Bacillus, and Pseudomonas spp. Notably, 83.3% of strains were resistant to Penicillin, Tetracycline, Amoxicillin, Ampicillin, and Erythromycin but 16.6% showed antibiotic susceptibility to the above-mentioned commonly used antibiotics. Silkworm larvae fed on penicillin-treated leaves showed significant improvement in larval weight, larval length, and cocoon production. Significantly higher larval weight (6.88g), larval length (5.84cm), and cocoon weight (1.33g) were recorded for larvae fed on leaves treated with penicillin as compared to other antibiotics. Isolated bacterial strains showed close relation with Serratia spp., Bacillus spp. and Pseudomonas spp.

Towards Functional Insect Feeds: Agri-Food By-Products Enriched with Post-Distillation Residues of Medicinal Aromatic Plants in Tenebrio molitor (Coleoptera: Tenebrionidae) Breeding

Sustainability, circular economy and alternative production systems are urgent imperatives for humanity and animal husbandry. Unless wasted, agri-food by-products can offer a promising source of high value. We evaluated the effect of rice bran (RB), corncob (CC), potato peels (PP), solid biogas residues (BR), and olive-oil processing residuals (OR), as alternative substrates to wheat bran (WB as control), on the growth and nutritional value of Tenebrio molitor during its breeding for animal feeds and/or human consumption. Innovation-wise, we further investigated the substrate supplementation (0, 10, 20%) with post-distillation residues of Mediterranean aromatic-medicinal plants (MAPs: lavender, Greek oregano, rosemary, olive; 1:1:1:1 ratio). Tenebrio molitor larvae (TML) were reared in all the studied substrates, and TML and diets’ proximate and fatty acid compositions as well as total phenol and flavonoid content and antioxidant potential were assessed using standard procedures. After statistical analysis of correlations, we observed that CC promoted oviposition and progeny survival; larval weight and dry matter were positively affected mainly by dietary energy and fat content; number of TML and/or larval weight increased using 10% MAPs inclusion in WB, RB and OR or RB, OR, BR and PP, respectively, which did not affect protein content; TML fatty acid composition decreased the content of saturated ones and increased that of mono-unsaturated ones; MAPs residues had an apparent favorable impact on total phenolic content and antioxidant activity of each substrate, with RB displaying the highest capacity and content. These findings indicate that alternative substrates can be exploited and their enrichment with natural phenolics is able to influence T. molitor growth, offering highly beneficial and nutritional value.

​Screening of Pigeonpea Varieties through Nylon Bag No-choice Bioassay for Host Plant Resistance to Helicoverpa armigera

Background: The legume pod borer, Helicoverpa armigera (Hübner), is one of the most damaging crop pests, including pigeonpea. Host plant resistance is a component of pest management and therefore, we standardize a nylon bag No-Choice Bioassay technique to screen for resistance to H. armigera under field conditions. Methods: Pigeonpea plants were infested with 24 h old 1, 2, 3, 4 and 5 larvae per plant inside the nylon bag. Observations were recorded on pod damage, larval survival, larval weight, pupation, adult emergence, and fecundity after 10 days. Result: Pigeonpea varieties AL-201, H03-41 and PAU-881 exhibited lower pod damage (15.89 to 19.77%) and larval weight (12.02 to 13.82 mg). The expression of resistance to H. armigera was associated with trichome density, pod wall thickness and higher amount of phenolic compounds and condensed tannins. Lower trichome density and thin pod walls and higher amounts of sugars rendered the varieties Paras, Manak and Pussa-992 more susceptible to H. armigera. Nylon bag assay can be used to screen and select pigeonpea cultivars for resistance to H. armigera.

Impact of Biochar on Douglas-Fir Tussock Moth (Orgyia pseudotsugata Lepidoptera: Erebidae) Larvae Reared on Synthetic Die

The use of biochar as a soil amendment in forest ecosystems can be beneficial in the restoration of degraded soils. Forest insects such as the Douglas-fir tussock moth, Orgyia pseudotsugata (McDonnough) (Lepidoptera: Erebidae), may be exposed to biochar when the material is applied. Two experiments were conducted using biochar either (1) applied to the surface of the diet at three rates (0, 5, and 10 mg) or (2) incorporated into synthetic diet at four rates (0, 10, 20, and 40% volume/volume). The objective of both experiments was to determine if biochar on the surface or incorporated into a synthetic diet affected development and survival of O. pseudotsugata larvae. In both experiments, there was a significant decrease in estimated time to larval mortality in all biochar treatments compared to untreated controls. In the surface-applied biochar experiment, there was a significant difference in larval weight gain at day 12 between the control and 10 mg biochar treatments. In the experiment with biochar incorporated into the diet, mean larval weight at day 12 was highest in the low (10%) biochar treatment compared to all other treatments, although weight gain was only significantly different between the low- and high-concentration (40%) biochar treatments. Our results suggest that larvae, feeding on a low amount of biochar in the synthetic diet, may respond by engaging in compensatory feeding behavior. Fewer surviving larvae in the biochar treatment groups may contribute to the lack of significance found in the comparison of weight gain at day 24 in each experiment.

Supplementation of Lactobacillus casei reduces the mortality of Bombyx mori larvae challenged by Nosema bombycis

Objective Pebrine, caused by the microsporidium Nosema bombycis, is one of the severe diseases in Thai polyvoltine strains of the silkworm Bombyx mori. Studies showing the presence of Lactobacillus species in the silkworm gut, where the Nosema parasites enter, suggests that these bacteria may have a protective effect. The aim of this study was to investigate the effect of supplementation of Lactobacillus casei on the survival ratio of silkworm larvae challenged with N. bombycis. Results A group of silkworm larvae of the commercial Thai polyvoltine hybrid strain DokBua was supplemented with L. casei on the second day of the 2nd, 3rd, 4th, and 5th instar. When a control group of silkworm larvae were challenged with N. bombycis on the second day of the 4th instar, the survival rate was 68%, but it was 91% for larvae supplemented with L. casei. For those larvae that survived the treatments until pupation, we determined the growth characters larval weight, cocooning ratio, and pupation ratio, and the economic characters cocoon weight and cocoon shell weight. When infected with N. Bombycis, growth characters were significantly higher in larvae also receiving L. casei.

Siklus hidup Spodoptera frugiperda J.E. Smith dengan pakan daun bayam cabut hijau dan daun bayam duri hijau di laboratorium

Spodoptera frugiperda merupakan hama baru di Indonesia yang menyerang tanaman jagung dan memiliki berbagai macam tanaman inang lain. Salah satu tanaman yang dimungkinkan menjadi inang dari hama ini di Indonesia adalah bayam. Tujuan penelitian ini untuk mengetahui lama siklus hidup S. frugiperda yang diberikan pakan daun bayam cabut hijau dan daun bayam duri hijau. Metode penelitian ini yaitu permeliharaan S. furgiperda dengan sumber pakan yang berbeda dan mengamati beberapa parameter. Analisis statistik berupa inferensial, data yang dilakukan dengan uji normalitas Shapiro-Wilk. Apabila data normal dilakukan uji homogenitas dengan dilanjutkan analisis ANNOVA. Hasil penelitian menunjukan bahwa S. frugiperda pada pakan kontrol (daun jagung) memiliki lama siklus hidup 38 hari, daun bayam cabut hijau 40 hari, dan daun bayam duri hijau 42 hari. Panjang larva S. frugiperda paling panjang didapatan pada pakan daun bayam duri hijau, sedangkan diameter kepala tidak terdapat perbedaan antara ketiga pakan. Bobot larva paling berat didapatkan pada pakan daun bayam cabut hijau. Panjang dan berat pupa S. frugiperda paling tinggi didapatkan pada pakan daun bayam duri hijau. Jumlah jantan paling banyak dihasilkan pada pakan daun bayam cabut hijau dan daun bayam duri hijau, sedangkan jumlah betina paling banyak dihasilkan pakan kontrol. Jumlah telur paling banyak dihasilkan pada pakan kontrol dan paling sedikit pada bayam duri hijau. Pakan bayam cabut dan bayam duri daun bayam cabut hijau dan bayam duri hijau dapat digunakan sebagai pakan alternatif bagi S. frugiperda di laboratorium. Kata kunci: pakan alternatif; perkembangan; pertumbuhan; Spodoptera frugiperda ABSTRACTLife cycle of Spodoptera frugiperda J.E. Smith with green spinach and green thorn spinach leaves in the laboratory. Spodoptera frugiperda is a new pest in Indonesia that attacks maize and has a wide variety of other host plants. One of the plants that is possible to host this pest in Indonesia is spinach. The purpose of this study was to determine the length of the life cycle of S. frugiperda which was fed with green spinach leaves and green thorn spinach leaves. This research method is the maintenance of S. furgiperda with different feed sources and observing several parameters. Statistical analysis in the form of inferential, the data was done by using the Shapiro-Wilk normality test. If the data is normal, the homogeneity test is carried out followed by ANNOVA analysis. The results showed that S. frugiperda in control diets (corn leaves) had a life cycle length of 38 days, green spinach leaves 40 days, and green thorn spinach leaves 42 days. Thelarvae of longestS. frugiperda were found in green thorn spinach leaf feed, while there was no difference in head diameter between the three diets. The heaviest larval weight was found in green pulled spinach feed. Thelength and weight ofpupa were S. frugiperda highestfound in green thorn spinach leaf feed. The highest number of males was produced in green spinach leaf and green spinach leaf feed, while the highest number of females was produced in control feed. The highest number of eggs was produced in the control feed and the least was the green thorn spinach. Spinach feed and spinach spines, green pulled spinach and green spiny spinach can be used as an alternative feed for S. frugiperda in the laboratory. Keywords: alternative food; development; growth; Spodoptera frugiperda

Using organic wastes as feed substrate for black soldier fly larvae

Feeding black soldier fly larvae (BSFL) on locally available organic wastes has the potential of providing an alternative source of protein to fishmeal and soybean used in animal feed formulation. This can also mitigate against increasing accumulation of organic wastes and reduce high costs associated with their disposal. This study assessed the effects of three locally available organic waste substrates namely Irish potato peels, kale remains and bovine ruminal content versus chick mash as a positive control on larval weight gain, prepupal yield, substrate reduction rate, bioconversion rate and conversion ratio of BSFL. Analysis of variance (ANOVA) was used to determine whether organic feed substrates had significant effects on BSFL while Tukey HSD, post-hoc test was applied for multiple comparisons and mean separation at P<0.05. Organic waste feed substrates influenced larval weight gain and prepupal yield (P<0.01), biomass reduction rate (P=0.04), bioconversion rate (P=0.01) and conversion ratio (P=0.04) of BSFL produced. Kale remains performed better than Irish potato peels and bovine ruminal contents implying that they can be enriched to provide an alternative feed for BSFL instead of chick mash. This study demonstrated that the three locally available organic waste substrates can be used to feed BSFL for sustainable production of animal feed. Black soldier fly larvae have the potential of providing a viable solution for degradation and disposal of ever-increasing quantities of organic wastes in the markets, towns and cities of sub-Saharan Africa.

Antibiosis to Spodoptera frugiperda (Lepidoptera: Noctuidae) in chickpea genotypes

Chickpeas (Cicer arietinum L.) belong to the Fabaceae family and are one of the most grown crops in the world and an important source of protein for humans. Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) is a polyphagous pest that causes significant crop damage. The objective of this study was to examine antibiosis to S. frugiperda in chickpea genotypes. The following genotypes were studied: Jamu 96 and Blanco Sinaloa 92 (Mexico); Nacional 29 (Cuba); BG 1392 (Spain), and BRS Kalifa, BRS Cristalino, BRS Toro, Nacional 27, 004UP, 003UP, BRS Cícero, and BRS Aleppo (Brazil). The chickpea genotypes influenced the biological parameters of S. frugiperda, of which larval period, larval weight, and pupal period were most affected. Nacional 29 caused high mortality in the larval and pupal stages of S. frugiperda. The larvae on BRS Aleppo had the longest larval stage, lowest weight, and longest pupal stage. The genotypes Nacional 29, Nacional 27, and BRS Cícero showed antibiosis resistance to S. frugiperda. These genotypes could be used as a source of resistance to S. frugiperda in conjunction with other methods of pest control in integrated pest management programs for chickpea crops. These resistant genotypes could also be used as donor sources in breeding programs for insect resistance.

Effect of fecal matter co-digestion with kitchen waste on Hermetia illucens’s larval weight and protein content

Sustainable treatment of fecal matter is a long-standing challenge in sanitation, particularly in developing countries. Although recent developments have seen the evolution of innovative onsite sanitation technologies, the treatment of fecal waste collected still remains a daunting task. This study evaluated the effect of formulated feedstock: fecal matter from urine-diverting dry toilets and kitchen waste (1:0, 1:1, 2:1, 4:1, and 0:1) on waste weight reduction, Hermetia illucens’s larval weight gain, and crude protein content during co-digestion. Samples were collected after every 2 days for larval weight determination and protein content analysis using the Kjeldahl method of nitrogen determination. The waste reduction index (WRI) was determined after 50% pupation. The larvae grew on all substrates yielding 32.97–38.6% dry matter (DM) protein content and larval weight ranging from 1.12 to 1.70 g per five larvae. Results indicate that a 1:1 co-digestion ratio resulted in a high WRI (3.61), DM crude protein content (38.6%), and larval weight (1.70 g per five larvae). This study used the circular economy-based approach which provides a win–win situation to sanitation provision and environmental management while realizing products with potential for livelihood improvement.

Sea plant extract (Kappaphycus sp) - A boon to sericulture industry

A field experiment was conducted to evaluate the performance of sea plant extract sprayed on mulberry plant at different interval of time and the treated leaves were fed to the silkworm Bombyx mori which were infected with BmNPV. It was found that foliar application of sea plant extract, LBS 13 @ 1.5 ml/l on 45th day after pruning enhanced the leaf yield per plant by 308.81 g, average plant height by 150.42 cm, number of shoots (14.32) and leaves per plant (400 leaves) compared with control. When the treated leaves were fed to the BmNPV infected silkworms, LBS13 @ 1.5 ml/lrecorded highest larval weight (3.33 g/ larvae) with larval duration (7.67 days), least larval mortality (3.33 %) and disease incidence (11.33 %) when compared to control. The study evidenced that application of sea plant extract of Kappaphycus sp. has improved the growth attributes of mulberry, which inturn had a direct positive impact on development of B. mori.